Ceramic electronic component and manufacturing method thereof

ABSTRACT

A ceramic electronic component includes a ceramic body, an inner electrode, an outer electrode, and a connecting portion. The inner electrode is disposed inside the ceramic body. The end portion of the inner electrode extends to a surface of the ceramic body. The outer electrode is disposed on the surface of the ceramic body so as to cover the end portion of the inner electrode. The outer electrode includes a resin and a metal. The connecting portion is disposed so as to extend from an inside of the outer electrode to an inside of the ceramic body. In a portion of the surface of the ceramic body on which the outer electrode is disposed, the length of the connecting portion that extends in a direction in which the inner electrode is extends about 2.4 μm or more.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a ceramic electronic component and amethod for producing the ceramic electronic component.

2. Description of the Related Art

In recent years, ceramic electronic components such as monolithicceramic capacitors have been used in harsher environments than comparedwith before.

Ceramic electronic components used for mobile devices such as cellularphones and portable music players are required to withstand dropimpacts. Specifically, even if electronic components undergo dropimpacts, it is necessary that they will not easily become detached frommount boards and that cracks will not easily form in electroniccomponents.

Electronic components used for in-vehicle equipment such as ECUs arerequired to withstand the shock of a thermal cycle. Specifically, evenif mount boards undergo deflection stress caused when the mount boardsare subjected to thermal expansion and contraction due to a thermalcycle, it is necessary that cracks will not easily form in ceramicelectronic components and solder used to mount the electroniccomponents.

To satisfy such requirements, it has been proposed that an outerelectrode containing a resin be formed using a thermosetting conductivepaste instead of a conventional firing conductive paste. For example,WO2004/053901 discloses a ceramic electronic component including anouter electrode that is formed using a thermosetting conductive pastecontaining conductive particles with a high melting point, a metalpowder with a melting point of 300° C. or lower, and a resin with amelting point of 300° C. or lower.

In recent years, there has been an increasing demand for a furtherincrease in the bonding strength between an inner electrode and an outerelectrode.

SUMMARY OF THE INVENTION

Preferred embodiments of the present invention provide a ceramicelectronic component with high bonding strength between an innerelectrode and an outer electrode.

A ceramic electronic component according to a preferred embodiment ofthe present invention includes a ceramic body, an inner electrode, anouter electrode, and a connecting portion. The inner electrode isdisposed inside the ceramic body. The end portion of the inner electrodeextends to a surface of the ceramic body. The outer electrode isdisposed on the surface of the ceramic body so as to cover the endportion of the inner electrode. The outer electrode includes a resin anda metal. The connecting portion is disposed so as to extend from aninside of the outer electrode to an inside of the ceramic body. In aportion of the surface of the ceramic body on which the outer electrodeis formed, the length of the connecting portion that extends in adirection in which the inner electrode extends is about 2.4 μm or more.

In one aspect of the ceramic electronic component according to apreferred embodiment of the present invention, the connecting portioncontains the same metal as that contained in the outer electrode and thesame metal as that contained in the inner electrode.

In another aspect of the ceramic electronic component according to apreferred embodiment of the present invention, the outer electrodecontains a first metal component and a second metal component having ahigher melting point than the first metal component, and the connectingportion contains the first metal component.

In still another aspect of the ceramic electronic component according toa preferred embodiment of the present invention, the first metalcomponent contains Sn and the second metal component contains Ag.

In still yet another aspect of the ceramic electronic componentaccording to a preferred embodiment of the present invention, the innerelectrode contains Ni and the connecting portion contains a Sn—Ni alloy.

In still yet another aspect of the ceramic electronic componentaccording to a preferred embodiment of the present invention, the widthof a portion of the connecting portion located in the outer electrode islarger than the width of a portion of the connecting portion located inthe ceramic body.

In a method for producing a ceramic electronic component according toyet another preferred embodiment of the present invention, a ceramicbody is prepared that includes an inner electrode disposed inside theceramic body and in which an end portion of the inner electrode extendsto a surface of the ceramic body. An electrode layer is formed on thesurface of the ceramic body so as to cover the end portion of the innerelectrode, the electrode layer containing a resin, a first metal fillerthat contains a first metal component, and a second metal filler thatcontains a second metal component having a higher melting point than thefirst metal component. The electrode layer is heated to form, on thesurface of the ceramic body, an outer electrode that contains the resinand the first and second metal components and that is disposed so as tocover the end portion of the inner electrode and a connecting portionthat contains the first metal component and a metal contained in theinner electrode and that is disposed so as to extend from an inside ofthe outer electrode to an inside of the ceramic body.

In one aspect of the method for producing a ceramic electronic componentaccording to a preferred embodiment of the present invention, in theheating step, the electrode layer is heated to about 480° C. or higherin a non-oxidative atmosphere.

In another aspect of the method for producing a ceramic electroniccomponent according to a preferred embodiment of the present invention,in the heating step, the electrode layer is heated to a temperature oflower than about 800° C.

In still another aspect of the method for producing a ceramic electroniccomponent according to a preferred embodiment of the present invention,the first metal component contains Sn, and the second metal componentcontains Ag.

In still yet another aspect of the method for producing a ceramicelectronic component according to a preferred embodiment of the presentinvention, the inner electrode contains Ni.

According to various preferred embodiments of the present invention, aceramic electronic component with high bonding strength between theinner electrode and the outer electrode is provided.

The above and other elements, features, steps, characteristics andadvantages of the present invention will become more apparent from thefollowing detailed description of the preferred embodiments withreference to the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic perspective view of a ceramic electronic componentaccording to a preferred embodiment of the present invention.

FIG. 2 is a schematic sectional view showing a cross section thatextends in the length direction L and the thickness direction T of theceramic electronic component according to a preferred embodiment of thepresent invention.

FIG. 3 is a schematic sectional view taken along line III-III of FIG. 2.

FIG. 4 is a schematic sectional view taken along line IV-IV of FIG. 2.

FIG. 5 is a schematic sectional view of a V portion of FIG. 2.

FIG. 6 is a schematic sectional view for describing the productionprocess of the ceramic electronic component according to a preferredembodiment of the present invention.

FIG. 7 is a photograph showing a partially enlarged cross section of aceramic electronic component prepared in Experimental Example 8.Specifically, FIG. 7 is a scanning electron micrograph obtained byobserving a portion of the ceramic electronic component prepared inExperimental Example 8 at an acceleration voltage of 15.0 kV with amagnification of 5000×.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

An example of preferred embodiments of the present invention will now bedescribed. Note that the preferred embodiments described below aremerely examples. The present invention is not limited to the preferredembodiments described below.

In the drawings referred to in the description of preferred embodiments,components having substantially the same function are denoted by thesame reference numerals. The drawings referred to in the description ofpreferred embodiment are schematically described, and the size ratio ofobjects drawn in the drawings may be different from that of actualobjects. The size ratio of objects may also be different between thedrawings. The specific size ratio of objects should be judged by takingthe following description into consideration.

FIG. 1 is a schematic perspective view of a ceramic electronic componentaccording to a preferred embodiment of the present invention. FIG. 2 isa schematic sectional view showing a cross section that extends in thelength direction L and the thickness direction T of the ceramicelectronic component according to the present preferred embodiment. FIG.3 is a schematic sectional view taken along line III-III of FIG. 2. FIG.4 is a schematic sectional view taken along line IV-IV of FIG. 2. FIG. 5is a schematic sectional view of a V portion of FIG. 2. First, thestructure of a ceramic electronic component 1 according to the presentpreferred embodiment will be described with reference to FIGS. 1 to 5.

The ceramic electronic component 1 includes a ceramic body 10. Theceramic body 10 preferably has a rectangular parallelepiped shape, forexample. The ceramic body 10 includes first and second principalsurfaces 10 a and 10 b that extend in the length direction L and thewidth direction W, first and second side surfaces 10 c and 10 d thatextend in the thickness direction T and the length direction L, andfirst and second end surfaces 10 e and 10 f that extend in the thicknessdirection T and the width direction W.

In preferred embodiments of the present invention, the “rectangularparallelepiped shape” includes a rectangular parallelepiped whosecorners and ridge lines are rounded. That is, a “rectangularparallelepiped” component includes any component having first and secondprincipal surfaces, first and second side surfaces, and first and secondend surfaces. Furthermore, depressions and projections may be partiallyor entirely formed on the principal surfaces, side surfaces, and endsurfaces.

The ceramic body 10 is composed of a suitable ceramic material. The typeof ceramic material constituting the ceramic body 10 can be suitablyselected in accordance with desired characteristics of the ceramicelectronic component 1.

For example, when the ceramic electronic component 1 is a capacitor(monolithic ceramic capacitor), the ceramic body 10 can be formed of adielectric ceramic material. Examples of the dielectric ceramic materialinclude BaTiO₃, CaTiO₃, SrTiO₃, CaZrO₃, MgTiO₃, MgTiO₃—CaTiO₃, TiO₂ andBaTiO₃—Nd₂O₃—TiO₂.

For example, when the ceramic electronic component 1 is a piezoelectriccomponent, the ceramic body 10 can be formed of a piezoelectric ceramicmaterial. An example of the piezoelectric ceramic material is a PZT(lead zirconate titanate) ceramic material.

For example, when the ceramic electronic component 1 is a thermistor,the ceramic body 10 can be formed of a semiconductor ceramic material.An example of the semiconductor ceramic material is a spinel-typeceramic material.

For example, when the ceramic electronic component 1 is an inductor, theceramic body 10 can be formed of a magnetic ceramic material. An exampleof the magnetic ceramic material is a ferrite ceramic material.

As shown in FIGS. 2 to 4, inside the ceramic body 10, a plurality offirst and second inner electrodes 25 and 26 each having a substantiallyrectangular shape are alternately arranged at regular intervals in thethickness direction T. The first and second inner electrodes 25 and 26are parallel or substantially parallel to the first and second principalsurfaces 10 a and 10 b. In the thickness direction T, the first andsecond inner electrodes 25 and 26 face each other with a ceramic layer10 g therebetween. The thickness of the ceramic layer 10 g is, forexample, preferably about 0.5 μm to about 10 μm.

The end portions of the first and second inner electrodes 25 and 26 areled to the surface of the ceramic body 10. Specifically, the first innerelectrode 25 is exposed on the first end surface 10 e, and is notexposed on the first and second principal surfaces 10 a and 10 b, thesecond end surface 10 f, and the first and second side surfaces 10 c and10 d. The second inner electrode 26 is exposed on the second end surface10 f, and is not exposed on the first and second principal surfaces 10 aand 10 b, the first end surface 10 e, and the first and second sidesurfaces 10 c and 10 d. Specifically, the end portions of the first andsecond inner electrodes 25 and 26 are slightly depressed from the firstand second end surfaces 10 e and 10 f, respectively.

The first and second inner electrodes 25 and 26 can be composed of asuitable conductive material, e.g., a metal such as Ni, Cu, Ag, Pd, orAu or an alloy containing at least one of the foregoing metals, such asa Ag—Pd alloy. In particular, the first and second inner electrodes 25and 26 preferably contain Ni. Specifically, the first and second innerelectrodes 25 and 26 are preferably composed of, for example, Ni or aNi-containing alloy such as Ni—Cu.

The thicknesses of the first and second inner electrodes 25 and 26 are,for example, each preferably about 0.2 μm to about 2.0 μm.

First and second outer electrodes 13 and 14 are disposed on the surfaceof the ceramic body 10. Specifically, the first outer electrode 13 isdisposed so as to cover the first end surface 10 e on which the firstinner electrode 25 is exposed. The first outer electrode 13 is disposedso as to reach the first and second principal surfaces 10 a and 10 b andthe first and second side surfaces 10 c and 10 d. The first outerelectrode 13 is electrically connected to the first inner electrode 25.

The second outer electrode 14 is disposed so as to cover the second endsurface 10 f on which the second inner electrode 26 is exposed. Thesecond outer electrode 14 is disposed so as to reach the first andsecond principal surfaces 10 a and 10 b and the first and second sidesurfaces 10 c and 10 d. The second outer electrode 14 is electricallyconnected to the second inner electrode 26.

The first and second outer electrodes 13 and 14 each include a firstconductive layer 15 and a second conductive layer 16. The firstconductive layer 15 is disposed directly on the surface of the ceramicbody 10. Specifically, the first conductive layer 15 is disposed so asto cover the first end surface 10 e or the second end surface 10 f andreach the first and second principal surfaces 10 a and 10 b and thefirst and second side surfaces 10 c and 10 d. Herein, the firstconductive layer 15 may be disposed only on the first end surface 10 eor the second end surface 10 f.

The thickness of the first conductive layer 15 is, for example,preferably about 5.0 μm to about 70.0 μm.

The second conductive layer 16 is disposed on the first conductive layer15. The first conductive layer 15 is substantially covered with thesecond conductive layer 16. The second conductive layer 16 is preferablycomposed of a plating film, for example. The second conductive layer 16may be composed of a single plating film or a laminated body of multipleplating films. Specifically, the second conductive layer 16 is disposedon the first conductive layer 15 and may be composed of a laminated bodyof a Ni plating layer that also serves as a barrier layer and a platinglayer that is disposed on the Ni plating layer and contains Sn or Au,which has good wettability. The thickness of each of the plating layersconstituting the second conductive layer 16 is, for example, preferablyabout 1 μm to about 15 μm.

The first conductive layer 15 contains a first metal component, a secondmetal component, and a resin. In the first conductive layer 15, thefirst and second metal components are disposed in a resin matrix, andthe first and second metal components provide conductivity of the firstconductive layer 15. The first and second metal components may bealloyed with each other.

Since the first conductive layer 15 contains a resin, it is moreflexible than a conductive layer composed of, for example, a platingfilm or a fired product of conductive paste. Therefore, even if theceramic electronic component 1 is subjected to physical impact or theshock caused by a thermal cycle, the first conductive layer 15 functionsas a shock absorbing layer. Thus, the ceramic electronic component 1 isnot easily damaged and solder used to mount the ceramic electroniccomponent 1 is also not easily damaged.

Preferred examples of the resin added to the first conductive layer 15include thermosetting resins such as an epoxy resin and a phenolicresin.

The content of the resin in the first conductive layer 15 after curingis preferably about 46% to about 77% by volume, for example.

The melting point of the first metal component is relatively low and themelting point of the second metal component is relatively high. Themelting point of the first metal component is, for example, preferablyabout 550° C. or lower and more preferably about 180° C. to about 340°C. The melting point of the second metal component is, for example,preferably about 850° C. to about 1050° C.

The first metal component is preferably composed of, for example, Sn,In, or Bi or an alloy containing at least one of the foregoing metals.In particular, the first metal component is more preferably composed ofSn or an alloy containing Sn. Examples of the alloy containing Sninclude Sn—Ag, Sn—Bi, and Sn—Ag—Cu.

The content of the first metal component in the first conductive layer15 after curing is preferably about 8% to about 18% by volume, forexample.

The second metal component is preferably composed of, for example, ametal such as Ag, Pd, Pt, or Au or an alloy containing at least one ofthe foregoing metals. In particular, the second metal component is morepreferably composed of Ag or a Ag alloy such as a Ag—Pd alloy.

The content of the second metal component in the first conductive layer15 after curing is preferably about 19% to about 25% by volume, forexample.

The first conductive layers 15 of the outer electrodes 13 and 14 areconnected to the respective inner electrodes 25 and 26 through aconnecting portion 18. The connecting portion 18 is disposed so as toextend from the inside of each of the outer electrodes 13 and 14 to theinside of the ceramic body 10. In the portion (end surfaces 10 e and 10f) of the surface of the ceramic body 10 on which the outer electrodes13 and 14 are disposed, the length L of the connecting portion 18 thatextends in the direction (length direction) in which the innerelectrodes 25 and 26 are led is about 2.4 μm or more, for example. Thelength L of the connecting portion 18 is preferably about 9.6 μm orless, for example.

The width W1 of a portion of the connecting portion 18 formed in each ofthe outer electrodes 13 and 14 is larger than the width W2 of a portionof the connecting portion 18 formed in the ceramic body 10.

The connecting portion 18 preferably contains the same metal as thatcontained in the outer electrodes 13 and 14 and the same metal as thatcontained in the inner electrodes 25 and 26. The connecting portion 18more preferably contains the first metal component having a relativelylow melting point. For example, in the case where the first metalcomponent contains Sn and the inner electrodes 25 and 26 contain Ni, theconnecting portion 18 preferably contains a Sn—Ni alloy.

A non-limiting example of a method for producing the ceramic electroniccomponent 1 will now be described.

First, a ceramic body 10 including first and second inner electrodes 25and 26 is prepared. Specifically, a ceramic paste containing a ceramicpowder is applied in a sheet-shaped configuration by screen printing orother suitable process and then dried to produce a ceramic green sheet.Subsequently, a conductive paste for forming inner electrodes is appliedon the ceramic green sheet in a predetermined pattern by screen printingor other suitable process. Thus, a ceramic green sheet on which aconductive pattern for forming inner electrodes has been formed and aceramic green sheet on which a conductive pattern for forming innerelectrodes is not formed are prepared. Note that a publicly known binderor solvent may be contained in the ceramic paste and the conductivepaste for forming inner electrodes.

Next, a predetermined number of ceramic green sheets on which aconductive pattern for forming inner electrodes is not formed arestacked on top of each other. Ceramic green sheets on which a conductivepattern for forming inner electrodes has been formed are stacked thereonsuccessively. A predetermined number of ceramic green sheets on which aconductive pattern for forming inner electrodes is not formed arefurther stacked thereon. As a result, a mother stack is produced. Themother stack may be optionally subjected to pressing in the stackingdirection by isostatic pressing or other suitable process.

The mother stack is then cut into a plurality of green ceramic bodieseach having a predetermined shape and size. The green ceramic bodies maybe subjected to barrel polishing to round the ridge lines and cornersthereof.

Next, by firing each of the green ceramic bodies, a ceramic body 10 iscompleted that includes first and second inner electrodes 25 and 26disposed inside the ceramic body 10 and in which the end portions of thefirst and second inner electrodes 25 and 26 are led to the first andsecond end surfaces 10 e and 10 f, respectively. The firing temperatureof the green ceramic bodies can be suitably set in accordance with theceramic material and conductive material used. The firing temperature ofthe green ceramic bodies can be, for example, about 900° C. to about1300° C.

A paste for forming outer electrodes is then prepared that contains aresin 17 c such as a thermosetting resin, a first metal filler 17 acontaining a first metal component, and a second metal filler 17 bcontaining a second metal component having a higher melting point thanthe first metal component.

In this paste, the content of the first metal filler 17 a relative tothe total weight of the first metal filler 17 a, the second metal filler17 b, and the resin 17 c is preferably about 20% to about 40% by weightand more preferably about 22.0% to about 37.2% by weight, for example.If the content of the first metal filler 17 a is excessively low, aconnecting portion 18 is sometimes not sufficiently formed. If thecontent of the first metal filler 17 a is excessively high, the amountof first metal filler 17 a that does not react with the second metalfiller 17 b and is left in outer electrodes 13 and 14 increases. As aresult, the outer electrodes 13 and 14 may be deformed, for example, dueto heat applied during reflowing.

The shape of the first metal filler 17 a is not particularly limited.The first metal filler 17 a may have a spherical shape, a flat shape, orother suitable shape.

The average particle size of the first metal filler 17 a is notparticularly limited and may be, for example, about 1.0 μm to about 10μm.

In this paste, the content of the second metal filler 17 b relative tothe total weight of the first metal filler 17 a, the second metal filler17 b, and the resin 17 c is preferably about 30% to about 70% by weightand more preferably about 41.2% to about 64% by weight, for example. Ifthe content of the second metal filler 17 b is excessively low, theconductivity of the outer electrodes 13 and 14 decreases and theequivalent series resistance (ESR) of the ceramic electronic component 1may increase. If the content of the second metal filler 17 b isexcessively high, the content of the resin 17 c in the outer electrodes13 and 14 excessively decreases. As a result, the stress relaxationeffect of the outer electrodes 13 and 14 may excessively degrade.

The shape of the second metal filler 17 b is not particularly limited.The second metal filler 17 b may have a spherical shape, a flat shape,or other suitable shape.

The average particle size of the second metal filler 17 b is notparticularly limited and may be, for example, about 0.5 μm to about 5.0μm.

In this paste, the content of the resin 17 c relative to the totalweight of the first metal filler 17 a, the second metal filler 17 b, andthe resin 17 c is preferably about 5% to about 40% by weight and morepreferably about 9.8% to about 31.5% by weight, for example. If thecontent of the resin 17 c is excessively low, the stress relaxationeffect of the outer electrodes 13 and 14 excessively degrade and thusimpacts generated when stress is applied from the outside are sometimesnot sufficiently absorbed by the outer electrodes 13 and 14. If thecontent of the resin 17 c is excessively high, the conductivity of theouter electrodes 13 and 14 decreases and the equivalent seriesresistance (ESR) of the ceramic electronic component 1 may increase.

As shown in FIG. 6, an electrode layer 17 is then formed by applying theabove-described paste onto the surface of the ceramic body 10. The pastecan be applied by various printing methods or a dipping method, forexample.

Next, the electrode layer 17 is heated. The heating temperature of theelectrode layer 17 is preferably higher than or equal to a temperature(temperature range in which the diffusion of the first metal componentto the outside of the electrode layer 17 is facilitated) at which thecrystalline state of an alloy of the first metal component and thesecond metal component changes thermodynamically. The heatingtemperature of the electrode layer 17 is, for example, preferably about480° C. or higher. The electrode layer 17 is preferably heated in anon-oxidative atmosphere, e.g., a reducing atmosphere or a neutralatmosphere such as a nitrogen gas atmosphere. The electrode layer 17 ispreferably heated in an atmosphere whose oxygen concentration is about100 ppm or less, for example. By heating the electrode layer 17 to sucha high temperature, the outer electrodes 13 and 14 that contain theresin and the first and second metal components and are disposed so asto cover the end portions of the inner electrodes 25 and 26 and theconnecting portion 18 that contains the first metal component and themetal contained in the inner electrodes and is disposed so as to extendfrom the inside of each of the outer electrodes 13 and 14 to the insideof the ceramic body 10 are formed on the surface of the ceramic body 10.

If the heating temperature of the electrode layer 17 is excessivelyhigh, the first conductive layer 15 containing the resin 17 c issometimes not suitably formed. Thus, the heating temperature of theelectrode layer 17 is preferably lower than about 800° C. and morepreferably about 650° C. or lower.

Finally, by forming a second conductive layer 16 by a plating method orother suitable process, a ceramic electronic component 1 can becompleted.

As described above, since the outer electrodes 13 and 14 contain theresin 17 c in this preferred embodiment, the ceramic electroniccomponent 1 is excellent in terms of impact resistance and resistance toa thermal cycle. In addition, the length L of the connecting portion 18is preferably set to be about 2.4 μm or more, for example. This achieveshigh bonding strength between the inner electrodes 25 and 26 and therespective outer electrodes 13 and 14.

To further increase the bonding strength between the inner electrodes 25and 26 and the respective outer electrodes 13 and 14, the connectingportion 18 preferably contains the same metal as that contained in theouter electrodes 13 and 14 and the same metal as that contained in theinner electrodes 25 and 26. The connecting portion 18 more preferablycontains the first metal component and the same metal as that containedin the inner electrodes 25 and 26.

Preferred embodiments of the present invention will now be furtherdescribed in detail based on specific non-limiting experimentalexamples. However, the present invention is not limited by theexperimental examples below and may be modified without departing fromthe scope of the present invention.

Ceramic electronic components each having the same structure as that ofthe ceramic electronic component 1 according to the above-describedpreferred embodiment were prepared under the conditions below. For eachof the conditions, 5000 ceramic electronic components were prepared.Subsequently, the insulation resistance between an outer electrode andan inner electrode was measured under the conditions below. Sampleshaving an insulation resistance of 100 MΩ or less were defined as poorsamples, and the number of poor samples were counted. Table 1 shows theresults. In this experiment, insulation resistance was used as an indexof the bonding strength between the inner electrode and the outerelectrode. Herein, the following phenomenon is used. When the bondingstrength between the inner electrode and the outer electrode is low,that is, when the contact resistance between the inner electrode and theouter electrode is high, the charging rate of a capacitor decreases. Inthe case where a capacitor is charged within a short time, the charge iscompleted in samples having low contact resistance and the flow ofelectric current stops. Consequently, a high resistance value ismeasured. In contrast, the charge is not completed in samples havinghigh contact resistance and the flow of electric current continues.Consequently, a low resistance value is measured.

The length of a connecting portion was measured as follows. First, threesamples were picked out from each of the sample groups. For each of thesamples, about half of the volume of the sample was polished in thewidth direction so that the LT cross section shown in FIG. 2 wasexposed. Subsequently, the LT cross section was observed with anelectron microscope, and the lengths of three arbitrary connectingportions located in about half of the samples in the T direction on oneof the outer electrodes were measured. In such a manner, nine lengthswere measured for each of the sample groups, and the average value ofthe nine lengths was defined as the length of the connecting portion.Table 1 shows the results. The reason why the lengths were measured onone of the outer electrodes is that there is assumed to be no largedifference in the formation state of the connecting portion because apair of outer electrodes are symmetrically formed. The reason why thelengths of three arbitrary connecting portions located in about half ofthe samples in the T direction were measured is that there is assumed tobe no large difference in the length of the connecting portion in the Tdirection.

FIG. 7 is a photograph showing a partially enlarged cross section of aceramic electronic component prepared in Experimental Example 8.

Size of ceramic body 10: 1.0 mm×0.5 mm×0.5 mm

Ceramic material: BaTiO₃

Thickness of ceramic layer 10 g: 1.90 μm

Material of inner electrodes 25 and 26: Ni

Thickness of inner electrodes 25 and 26: 0.61 μm

Number of inner electrodes 25 and 26: 156

Distance from outermost inner electrode to principal surface (thicknessof outer layer on one side): 60 μm

Resin 17 c: thermosetting epoxy resin

Content of first metal filler relative to the total amount of firstmetal filler, second metal filler, and resin 17 c: 25.6% by weight

Content of second metal filler relative to the total amount of firstmetal filler, second metal filler, and resin 17 c: 60% by weight

Content of resin 17 c relative to the total amount of first metalfiller, second metal filler, and resin 17 c: 14.4% by weight

Heat treatment atmosphere: nitrogen gas atmosphere

Heat treatment time: shown in Table 1

Heat treatment temperature: shown in Table 1

Second conductive layer 16: laminated body of Ni plating layer and Snplating layer (Sn plating layer forms an outermost layer)

Measurement Conditions of Insulation Resistance

Charging voltage: 2.5 V

Charging time: 30 ms

Discharging time: 3 ms

TABLE 1 Heat Heat Length of Number of poor treatment treatmentconnecting samples/number temperature time portion of samplesExperimental 450° C. 90 minutes 1.8 μm 1055/5000  Example 1 Experimental450° C. 120 minutes  2.4 μm 606/5000 Example 2 Experimental 480° C. 30minutes 3.1 μm 661/5000 Example 3 Experimental 500° C. 13 minutes 2.5 μm798/5000 Example 4 Experimental 500° C. 18 minutes 2.8 μm 645/5000Example 5 Experimental 500° C. 30 minutes 3.2 μm 457/5000 Example 6Experimental 550° C. 13 minutes 2.9 μm 596/5000 Example 7 Experimental550° C. 18 minutes 3.8 μm 606/5000 Example 8 Experimental 550° C. 30minutes 5.2 μm 635/5000 Example 9 Experimental 550° C. 90 minutes 9.6 μm386/5000 Example 10 Experimental 600° C. 13 minutes 4.6 μm 582/5000Example 11 Experimental 600° C. 18 minutes 5.0 μm 600/5000 Example 12Experimental 600° C. 30 minutes 5.3 μm 546/5000 Example 13 Experimental650° C. 18 minutes 5.6 μm 463/5000 Example 14 Experimental 650° C. 90minutes 11.2 μm  2119/5000  Example 15

As is clear from the results shown in Table 1, the number of poorsamples is large in Experimental Example 1 in which the length of theconnecting portion is 1.8 μm. It is also clear that the number of poorsamples is large in Experimental Example 15 in which the length of theconnecting portion is 11.2 μm. However, in Experimental Example 15, itis assumed that, as a result of excessive growth of the connectingportion, the connecting portion lifts up the first conductive layer andthus contact failure is generated. Therefore, this mode is believed tobe different from that in Experimental Example 1. In addition to theExperimental Examples shown in Table 1, an experiment was performed at aheat treatment temperature of 800° C. However, in this experiment, theresin 17 c was scattered and thus the outer electrodes substantially didnot contain the resin 17 c.

While preferred embodiments of the present invention have been describedabove, it is to be understood that variations and modifications will beapparent to those skilled in the art without departing from the scopeand spirit of the present invention. The scope of the present invention,therefore, is to be determined solely by the following claims.

The invention claimed is:
 1. A ceramic electronic component comprising:a ceramic body; an inner electrode that is disposed inside the ceramicbody and including an end portion extending towards a surface of theceramic body, the inner electrode includes a metal; an outer electrodelayer that is disposed directly on the surface of the ceramic body so asto directly cover the end portion of the inner electrode, the outerelectrode layer includes a thermosetting resin and a metal; and aconnecting portion disposed so as to extend from an inside of the outerelectrode layer to an inside of the ceramic body; wherein in a portionof the surface of the ceramic body on which the outer electrode layer isdirectly disposed, a length of the connecting portion that extends in adirection in which the inner electrode extends is 2.4 μm or more; theconnecting portion includes an alloy including both of a same metal asthe metal included in the outer electrode layer and a same metal as themetal included in the inner electrode; the metal included in the outerelectrode layer is provided between the connecting portion and at leastone other connecting portion, such that the connecting portion and theat least one other connecting portion are connected by the metalincluded in the outer electrode layer; the connecting portion extendsfrom inside the ceramic body to outside the ceramic body at the surfaceof the ceramic body to which the end portion of the inner electrodeextends towards; a portion of the connecting portion located outside theceramic body at the surface of the ceramic body is wider than a portionof the connecting portion located inside the ceramic body at the surfaceof the ceramic body; and a portion of the thermosetting resin includedin the outer electrode layer is directly in contact with the surface ofthe ceramic body.
 2. The ceramic electronic component according to claim1, wherein the outer electrode layer includes a first metal componentand a second metal component having a higher melting point than thefirst metal component.
 3. The ceramic electronic component according toclaim 2, wherein the first metal component contains Sn and the secondmetal component contains Ag.
 4. The ceramic electronic componentaccording to claim 3, wherein the inner electrode contains Ni and theconnecting portion contains a Sn—Ni alloy.
 5. The ceramic electroniccomponent according to claim 1, wherein a width of a portion of theconnecting portion located in the outer electrode layer is larger than awidth of a portion of the connecting portion located in the ceramicbody.
 6. A ceramic electronic component comprising: a ceramic body; aninner electrode that is disposed inside the ceramic body and includingan end portion extending towards a surface of the ceramic body, theinner electrode includes a metal; an outer electrode layer that isdisposed directly on the surface of the ceramic body so as to directlycover the end portion of the inner electrode, the outer electrode layerincludes a thermosetting resin and a metal; and a connecting portiondisposed so as to extend from an inside of the outer electrode layer toan inside of the ceramic body; wherein the connecting portion includesboth of a same metal as the metal included in the outer electrode layerand a same metal as the metal included in the inner electrode; the metalincluded in the outer electrode layer is provided between the connectingportion and at least one other connecting portion, such that theconnecting portion and the at least one other connecting portion areconnected by the metal included in the outer electrode layer; theconnecting portion is disposed so as to extend from an inside of theouter electrode layer to an end portion of the inner electrode inside ofan end surface of the ceramic body; the connecting portion extends frominside the ceramic body to outside the ceramic body at the surface ofthe ceramic body to which the end portion of the inner electrode extendstowards; a portion of the connecting portion located outside the ceramicbody at the surface of the ceramic body is wider than a portion of theconnecting portion located inside the ceramic body at the surface of theceramic body; and a portion of the thermosetting resin included in theouter electrode layer is directly in contact with the surface of theceramic body.